859 FXUS66 KPQR 271626 AFDPQR Area Forecast Discussion National Weather Service Portland Oregon 925 AM PDT Tue Sep 27 2016 .SYNOPSIS...A weak front will weaken and dissipate over southwest Washington and northwest Oregon today, but not before bringing clouds, cooler temperatures and spotty precipitation to the area. The forecast area will be in between systems during the mid week period. The next low is expected to affect the area later in the week and on next weekend, bringing more clouds, cooler temperatures, and showers to the area, with snow possible this weekend over the higher Cascades. && .SHORT TERM...Today through Thursday...A weak front moved into southwest Washington and northwest Oregon overnight and this morning with clouds over a good part of the forecast area except the Cascades south of about Detroit. Precipitation has been spotty and mainly along the north coast and adjacent coastal mountains and in the south Washington Cascade foothills. Suspect the precipitation will not get much farther than that the rest of today. The front will continue to weaken and thin out through the day with some sunshine breaking through this afternoon. Temps should be much cooler than Monday, falling into the 70s today in most of the valleys. The models continue to say we will be in between systems after today, through tonight and Wednesday and into Thursday. This should lead to less clouds and more daytime sunshine. The models suggest we may see some clouds form along the Cascade foothills tonight and Wednesday morning and along the coast and coast range with less in the valleys though there may be some local valley fog. Night and morning clouds on Wednesday night and Thursday morning may be more confined to along the coast and inland around the Columbia River, with some patchy fog around again. Temps Wednesday will again be in the 70s in the valleys. The next low will be setting up off the coast Thursday and this will slowly cool the air mass, causing temps to fall a couple of degrees. There is a slight chance of some showers over the higher Cascades late Thursday and Thursday night with the main activity in Central Oregon. Tolleson .LONG TERM...No Changes. Previous discussion follows... (Thursday night through Monday)...Expect increasing clouds late Thursday night through Friday as the upper level trough advances south and east into the far eastern Pacific just offshore. The first round of rain will likely reach the coast by Friday afternoon, before pushing onshore in the evening. Still some timing differences for the various impulses rotating through the upper low, so it remains too early to pinpoint the timing and location of heaviest rainfall through the weekend, as well as just how much rain, but alternating periods of steady rain and drier weather with some lingering showers seem likely through the weekend. Another disturbance may arrive later Sunday or early Monday. Temperatures through the extended period will remain well below seasonal normals, only reaching the lower 60s at best from Friday through early next week. Snow levels begin quite high (generally above 8000 feet) on Thursday night, but quickly lower to 5500 feet by around midday Friday and remain between 5000 and 6000 feet through the weekend. Cullen && .AVIATION...MVFR stratus over much of most of the Willamette Valley this morning will gradually lift to vfr 17-18Z and scatter out 21-22Z. clouds obscuring coast range and some of the lower cascade slopes this morning through 19z. Front is in the dissipating stage along the coast from TMK to ONP with mvfr and some local ifr cigs and isolated drizzle through 18Z. Expect clouds to scatter out along the coast after 18z. local ifr visibility in fog will expected along the coast after 06z with mfr and local ifr stratus developing after 08z. patchy ifr fog expected over inland valleys aft 09. There is a possibility of some stratus developing in the southern Willamette Valley aft 12-15z Wednesday. Schneider KPDX AND APPROACHES...MVFR conditions will continue through 18-19z and scatter our around 21z. Schneider && .MARINE...High pressure will strengthen over the northeast Pacific today and linger through Wednesday. This will bring small craft advisory level northerly winds, particularly to the outer waters. Seas should also approach hazardous sea criteria later today due to them being especially steep and choppy. An area of weak low pressure will move into the northeast Pacific Friday and linger through the weekend, which should result in quieter weather across the waters, but there could be a brief southerly surge or two in winds. The main thing that will need to be watched is the possibility for a developing low pressure system to impact the waters late Sunday or Monday, possibly bringing gale force winds or higher. Confidence in this scenario remains low due to several models not showing this possibility at this point. /Neuman && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for winds until 3 PM PDT Wednesday for Waters from Cape Shoalwater WA to Florence OR from 10 to 60 nm. Small Craft Advisory for hazardous seas from noon today to 9 AM PDT Wednesday for Coastal Waters from Cape Shoalwater WA to Florence OR out 60 nm. Small Craft Advisory for winds from noon today to 10 PM PDT this evening for Coastal Waters from Cape Shoalwater WA to Florence OR out 10 nm. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.
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